MONTPELIER — An organic farmer turned to colleagues at his other job — state senator — to complain Friday about a vexing problem in the organic food movement: when a product can legitimately be labeled organic and when it should not be.

In more than a dozen emails sent to Sen. David Zuckerman, P/D-Chittenden, farmers around the state told of vegetable growers who have begun raising livestock to respond to a growing demand for locally raised meat. These growers are feeding their animals grain grown using conventional methods with chemical fertilizers and pesticides, the farmers claimed.

Most people don’t realize that even pigs or chickens promoted as pastured or free-range are still mostly fed conventional grain, Zuckerman said. And much of that grain is grown conventionally in other parts of the country.

The issue arises as an “organic” label that originated decades ago as the flag of a countercultural food movement since has become a marketing tool used to fetch higher prices for the products bearing the label, Zuckerman said.

The U.S. Department of Agriculture defines organic food as “produced without using most conventional pesticides; fertilizers made with synthetic ingredients or sewage sludge; bioengineering; or ionizing radiation.”

Zuckerman told the Senate Agriculture Committee that he did not have any specific legislation in mind — there’s little likelihood a bill written now would pass in the few remaining weeks in the 2013 session. But he said a bill addressing the problem might be warranted, and that late April was a good time to air the issue.

“This time of year, that’s a lot of marketing happening,” he said. “We’re going into the summer farmers market season.”

Eliot Burg, head of the consumer protection division at the Vermont attorney general’s office, said the office had sued and gotten several court settlements against companies falsely advertising their products as made in Vermont.

But, he said, “organic is not an issue that we have seen to date.”

Burg urged Vermont Organic Farmers, a group that has federal authorization to certify farms as organic, to put out information to farmers that is clear and easy to understand.